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World War 2, Western Australia, Rottnest Island, Bickley Battery, Observation Post and Command, Layout

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Overview

This multi-level building, constructed 1936-38, contains the Close Defence Battery Observation Post, the Search Light Director Control and a Battery Plotting Room. Internal communication was available through voice tubes. The building was splinter proof with steel doors and steel window shutters throughout.

Historical information

Because the principle sighting instrument of the time, the Depression Range Finder measured the range from its location to the target, the Clase Defence Battery Observation Post had to be close to the guns. At Bickley Battery, the Close Defence Observation Post is in line and equidistant between the F1 and F2, 6 inch Mk11 guns. This location also provided visual and verbal control of the battery location.
The Mk 11 guns had no automatic sights but were fitted with Vickers Receiver Dials not magslip. The two Depression Range Finders in the Observation Post each had Vickers Transmitters. There was Switching Gear which allowed either transmitter to work either one or both gun dials. This allowed the battery Commander if necessary to engage two targets simultaneously

The Searchlight Director Control was immediately adjacent to the Close Defence Battery Observation Post. It coordinated a small tepelphne exchange with lines yo all searchlights and searchlight engine rooms. There was a speaking tube to the Battery Observation Post.
The switchman was responsible for the correct elevation of the leading beam of light to illuminate the bow wave of the target and if possible the whole length of the target so that fall of shot could be observed.

At the time of construction, sighting technology necessitated that the Battery Plotting Room was located near the Close Defence Battery Observation Post. And adjacent to the Searchlight Director Controol. Five personnel were involved. By 1942, new technologies had seen changes and new facilities were built on Jubilee Hill.

Details

Registration number

cwa-org-32-54-527

Contextual Information

This entry is based on research, documentation and technical drawings prepared by John Mercer during many years as a leading member of the Rottnest Island Military Restoration Committee and the Defence Heritage Interpretation Plan Group.

Geotag

-32.008803670025, 115.55275977786

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Links to additional resources

Instrument - Converter No 103 Mk 1 (Aust)

Instrument - Coordinate Converter 2B Mk 3

Instrument - Depression Range Finder

Instrument - Travel Correction Calculator No 1 Mk 1

Australian Army Museum of Western Australia

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